Adaptive surgical tourniquet apparatus and method

Abstract

An adaptive surgical tourniquet comprises: an inflatable cuff for encircling a limb of a patient; pressurizing means for pressurizing the cuff; pressure relief means for depressurizing the cuff; cuff pressure sensing means for sensing cuff pressure; limb occlusion pressure sensing means for sensing the patient's initial limb occlusion pressure at a selected time; physiologic characteristic sensing means for sensing a physiologic characteristic of the patient; and pressure regulator means for establishing an adapted limb occlusion pressure that is a predetermined function of the initial limb occlusion pressure and the physiologic characteristic, wherein the pressure regulator means is operable after the initial limb occlusion pressure is sensed for selectably activating the pressurizing means and the pressure relief means to maintain the cuff pressure above the adapted limb occlusion pressure for a time period suitably long for the performance of a surgical procedure.

1. An adaptive surgical tourniquet, comprising:
 an inflatable cuff for encircling a limb of a patient; 
 pressurizing means for pressurizing the cuff; 
 pressure relief means for depressurizing the cuff; 
 cuff pressure sensing means for sensing cuff pressure; 
 limb occlusion pressure sensing means for sensing the patient's initial limb occlusion pressure at a selected time; 
 physiologic characteristic sensing means for sensing blood pressure of the patient; and 
 pressure regulator means operable after the initial limb occlusion pressure is sensed for selectably activating the pressurizing means and the pressure relief means to maintain the cuff pressure above an adapted limb occlusion pressure for a time period suitably long for the performance of a surgical procedure; 
 wherein the physiologic characteristic sensing means further senses a second physiologic characteristic of the patient, and wherein the pressure regulator means further establishes the adapted limb occlusion pressure to be a predetermined function of the initial limb occlusion pressure, the blood pressure and the second physiologic characteristic. 
 
     
     
       2. The adaptive surgical tourniquet as defined in  claim 1  wherein the limb occlusion pressure sensing means senses the patient's initial limb occlusion pressure by measuring arterial pulsations of blood flow in the limb distal to the cuff, by increasing the cuff pressure from a level near zero to a lowest level at the selected time when the arterial pulsations have a magnitude less than a minimum detection threshold, by producing the initial limb occlusion pressure to be indicative of the lowest level, and by decreasing the cuff pressure upon production of the initial limb occlusion pressure. 
     
     
       3. The adaptive surgical tourniquet as defined in  claim 1 , wherein the pressure regulator means further maintains the cuff pressure near a tourniquet pressure level having a predetermined relationship to the adapted limb occlusion pressure. 
     
     
       4. The adaptive surgical tourniquet as defined in  claim 1 , wherein the pressure regulator means further maintains the cuff pressure near a tourniquet pressure level equal to the sum of a first predetermined pressure level plus a second pressure level proportional to the value of the adapted limb occlusion pressure.